Open Source Unicycle? - Designs and technical discussion

Following the announcement that the BrakeFast adaptor is going to be an Open Source Hardware product, and most unicycles are using the free ISIS crank interface standard, it got me thinking about whether there’d be any merit to having fully Open Source unicycle component designs.

Companies already often work together on elements of designs or products, or just use parts produced by another company but specifically designed for unicycles:

  • Qu-Ax uses the KH design Eleven saddle
  • The KH36 used to use a variation of the Nimbus Stealth2 rim with braking surface, now they use a standard Stealth 2 and in Europe a Qu-Ax King George tyre
  • Florian Schlumpf worked with KH for the MUni Schlumpf hub

People have made freely available bicycle designs/components, why not unicycle components?

So, as some design practise, I’ve been making some parts (bearings, spacers, some hub parts, and a 36" Stealth 2 inspired rim so far).

I know people have created their own unicycle frames, freewheel hubs, geared hubs, 3D printed cranks and other accessories - how many of these are open designs? Would it be in any way useful to have these collated in one place for others to iterate on or work from in the future.

If anyone’s created something and would be happy for it to be an open design, but didn’t go any further than a paper napkin drawing, I’ll also put myself out there as being happy to recreate the part as a 3D model in Solidworks and/or FreeCAD.


I’m happy to share my Corbin V-36 design.

I have it in SketchUp somewhere…


Man the ISIS interface is a bit of a head scratcher to actually model.

Finally got there and my crank interface correctly meshes with my axle interface, complete with the correct sample pre-load spacing as defined in the specification so I’m calling it a success.

Now I just need to see if I can do it in FreeCAD!

Well I think the Brakefast idea came from my idea and subsequint making of the first disc adapter for the original Schlumpf hub and then the more recent versions that I gave away to my friends who had those hubs and to those who asked when I had them. But the best thing is how Roger and team put their heads together and made many improvements to the design/idea and now all my unicycle friends can have them. I had no intention of ever producing them since it was only, and still is a hobby of mine to make what I want. They are taking all the chances of producing a great product, and the financial hit. PROPS to them and thank you from the in frame schlumpf disc community! (Braking not through the gears)


Thanks for sharing, unicycle community! Imagine what would happen if unicycling were universally popular and if the Brakefast adapter were something everyone needed. The Bill Gates Foundation would have to intervene to make sure the adapter was 100% proprietary.


Just got invited to this website by a user on the Unicycling Discord. Here is my entry, a replication of the part that Ed Prat used to mount his perpendicular tubes for his pannier bags. Unfortunately I cant upload the Fusion 360 file to this thread, but I can show an image of it. Just contact me if you want the file.